Rear facing car seat advice needed

So I have a tall baby and had to purchase a britex marathon convertible car seat at 6 months. She just had her first birthday and I turned her seat around only to discover that although the law and minimum requirement is one year and 20 lbs ...the new recommendation is now 2 years old. This is my problem.

I have a 2009 prius and There just isn't enough space in the door frame for me to get my baby in the rear facing seat with out bumping her head or Hitting her bottom. She cries every time I put her in because its is so awkward. I tried putting the seat in the middle but it hurts my back to get her in ( I have herniated discs and some hip problems) and to top it off I just discovered today that I am not supposed to put RFCS in center because the latches are only for the side seats.

Is anyone else having this problem? I can't imagine her being able to fold and squeeze her in the small triangle of space bewteen the door frame and the car seat edge for another year. Should I give up on my Prius or just face her forward.